Field of the Invention
The present invention relates to wireless communication, and more particularly to a method and apparatus for performing self-interference cancellation (SIC or self-IC) in a full duplex radio (FDR) environment.
Discussion of the Related Art
Full duplex communication (FDR) technology can simultaneously perform transmission (Tx) and reception (Rx) at one node, such that system capacity of the FDR technology may be theoretically double that of legacy half duplex communication (HDC) technology in which time or frequency resources are divisionally used to be orthogonal to each other.
FIG. 1 is a conceptual diagram illustrating a user equipment (UE) and a base station (BS) configured to support FDR technology.
A total of three types of interferences may occur in the FDR situation shown in FIG. 1, and a detailed description thereof will hereinafter be given.
Intra-device Self-interference
First interference is intra-device self-interference. During the intra-device self-interference, data transmission/reception (Tx/Rx) is performed using the same time and frequency resources, such that not only a desired signal but also the transmitted signals are simultaneously received. In this case, the transmitted signals are received by a reception (Rx) antenna while attenuation is barely caused, and thus, are received with higher power than a desired signal.
UE to UE Inter-link Interference
Second interference is UE to UE inter-link interference. The UE to UE inter-link interference refers to interference caused by uplink signals that are transmitted from a UE and received by an adjacently positioned UE.
BS to BS Inter-link Interference
Third interference is BS to BS inter-link interference. The BS to BS inter-link interference refers to interference caused by signals that are transmitted between BSs or heterogeneous BSs (picocell, femtocell, and relay node) in a HetNet state and received by an Rx antenna of another BS.
Among the three types of interferences, the intra-device self-interference (hereinafter referred to as self-interference (SI)) is interference caused only in FDR, and may greatly deteriorate performance of the FDR system. In order to manage FDR, a most serious problem is cancellation of self-interference (SI). However, methods for effectively cancelling self-interference in an FDR state have not been discussed in detail.